Thanks, I have already found / followed a good guide on disassembling. I think might be right about the corrosion bridge. I actually thought I saw something like that (and rubbed a bit at it) but that was on the connector between the screen and main unit. However, unlike that connector, the Wi-Fi chip appears to be quite small, I am not sure where I'd find anything to clean up.

And my soldering is awful. I wouldn't try on soldering anything smaller than a wire.